The long-term objective of this small grant is to develop a computational fluid dynamics model to predict the concentration of polydisperse aerosols within the breathing zone of a worker. A pilot study to model monodisperse aerosol transport is proposed here. Because the deposition site of aerosols within the respiratory system depends on the particle size and density, a predictive model such as this would be useful for occupational exposure assessment in indoor work environments. Specific applications include: (1) quantitative judgment of particle concentration and size within the breathing zone for use in epidemiological studies, (2) selection of the appropriate personal protective equipment on the basis of particle size, (3) identification of the human-machine configurations which exacerbate or minimize risk of exposure to inspirable and respirable aerosols, and (3) testing the design of local exhaust ventilation systems to minimize these exposures. The pilot project will consist of writing a computer program to model the transport of monodisperse aerosols in the near wake of a bluff body representing the worker. Results of the numerical simulations will be compared with experimental data in order to evaluate the accuracy of the algorithm. Data from previous experiments have been made available to the investigators.